The study of methylation in the normal brain (rat and/or mouse) and a detailed examination of its pertubations arising as a result of the administration to intact animals of, or of the exposure of model neural systems to, the slow-acting convulsant agent L-methionine-dl-sulfoximine (MSO). We plan to study exclusively the methylations for which S-adenosyl-L-methionine (SAM) is the donor molecule. Histamine, selected catecholamines and indoleamines will serve as the small, and individual transfer ribonucleic acids, as the large molecular weight, methyl group acceptors.